The purpose of a thrust reverser during plane landing is to improve the braking capacity of a plane by redirecting forwards at least part of the thrust generated by the turbojet engine. In this phase, the reverser blocks the jet pipe propelling nozzle and directs the exhaust flow of the engine toward the front of the nacelle, thereby generating a counter-thrust that complements the braking of the wheels of the plane.
The means implemented to redirect the flow varies depending on the type of reverser. However, in all cases, the structure of a reverser includes mobile cowlings that are moveable between, firstly, a deployed position in which they open in the nacelle a passage intended for the deviated flow, and secondly, a stowed position in which they close this passage. These mobile cowlings can also perform a deviation function or simply an activation function for other deviation means.
In cascade reversers, for example, the mobile cowlings slide along rails such that when withdrawing during the opening phase, they uncover the deviation cascades arranged in the thickness of the nacelle. A system of rods connect this cowling to the blocking doors that are deployed inside the exhaust duct and block the direct flow output. In door reversers, conversely, each mobile cowling pivots such that it blocks the flow and deviates it and is therefore active in this redirecting.
In general, these mobile cowlings are actuated by hydraulic or pneumatic jacks that require a pressurized fluid delivery network. This pressurized fluid is classically obtained by air bleed on the turbojet engine in pneumatic systems, or taken from the plane's hydraulic circuit. Such systems require significant maintenance since small leaks in the hydraulic or pneumatic network may be difficult to detect and could have damaging effects on the inverser and other parts of the nacelle. Furthermore, on account of the limited space available in the front frame of the reverser, installing and protecting such a circuit is particularly difficult and bulky.
To overcome the various drawbacks related to pneumatic and hydraulic systems, manufacturers of thrust reversers have attempted to replace them and where possible to fit their reversers with electromechanical actuators, which are lighter and more reliable. Such a reverser is described in the document EP 0 843 089.
However, electromechanical actuators also have several drawbacks that need to be overcome to benefit fully from the advantages they bring in terms of mass and footprint gains.
In particular, electromechanical actuators require the use of a complete control system comprising the actuators, an electric motor adapted to drive the actuators, and control means for the motor and the actuators comprising an electrical circuit including power and control components, these components being susceptible to failure.
It is common in the event of failure of one of the components of this electrical circuit to shut down the control system in order to prevent any excessive overheating of this component that could cause an explosion due to the presence of explosive gases in the nacelle, or cause damage to nearby components by overheating.
Failure of one of the components of the electrical circuit often results in an increase in the intensity of the current passing through the electrical circuit.
Accordingly, the integration of a circuit breaker into the electrical circuit makes it possible to detect the failure of one of the components of the circuit and to shut down the control system if the current passing through the electrical circuit exceeds a predetermined threshold value.
However, the use of a circuit breaker does not enable detection of all component failures in the electrical circuit. Indeed, the failure of certain components has little or no effect on the intensity of the current passing through the electrical circuit.